An Introduction to Improved Biomass Cookstoves

‚Stoves 101‘

An introduction to improved biomass cookstoves

Christa Roth

FOODandFUEL consultant, Eschborn presented in cooperation with GIZ-HERA

Gesellschaft für Internationale Zusammenarbeit (GIZ) GmbH, Programme for Poverty oriented basic energy services

ETHOS, 28th January 2012 Kirkland Northwest University

„...When I get up in the morning

the first thing is to make fire...“

How about you?

What energy sources do you use?

Why?

What types of ‚stoves‘ do you have at home?

Christa Roth: Stoves 101 - An introduction to biomass cookstoves on 28.1.2012 ETHOS Kirkland

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We ALL need food to live

Most food needs to be cooked

For cooking we need energy (fuel)

Cooking energy accounts for >90% of

household energy in developing countries

Over 2.5 billion people use solid biomass

fuels (firewood, charcoal, dung, agricultural residues)

Firewood and charcoal are often from non-

renewable sources and getting scarce

In conventional fires they often cause

harmful emissions Christa Roth: Stoves 101 - An introduction to biomass cookstoves on 28.1.2012 ETHOS Kirkland

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common scenarios

wasteful

dangerous

smoky


How does fire burn?

Where is the hottest part of a flame?

What other conditions influence the performance of a fire?


What happens when biomass is burnt?

Solid

state

fuel

Gaseous

state

fuel

Emis-

sions

‚Wood‘-

gas

CO2 Water

vapour

-solid Gas

Raw

Bio-

mass

Water

vapour

Smoke

Dry Bio-

mass

Pyrolysis

Carboni-

sation

Char

gasifi-

cation

Bio-Char

dry-

ing

Heat

Combustion Gas-Air-Mix

sufficient O2

Ash

Combustion process

necessary inputs Heat from air for transformation O2

Legend: Transformation Input Output Design: Christa Roth

All processes occur simultaneously in an uncontrolled manner

Design: Christa Roth

Raw

Bio-

mass

Heat

Water

vapour

‚Wood‘-

gas

CO2Heat

Dry

Bio-

mass

Water

vapour

Bio-

Char Ash

Combustion process

solid Legend: Gas

O2 from air

Char

gasifi-

cation

Pyrolysis

Carboni-

sation

dry-

ing

Input

Combustion Gas-Air-Mix

Solid

state

fuel

Gaseous

state

fuel

Emis-

sions

necessary inputs

for transformation

Transformation

sufficient O2

Output

Smoke

What can we do to make this fire safer

for the users and their children?


contain and shelter the fire from wind


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How can we save energy?

Using improved stoves and fireless cookers -

technologies Keeping a lid on the pot, soaking legumes, using

less water, cooking for less time etc. -

techniques

How can we get more firewood? Cut the branch and not the tree

Plant trees or just let them grow

Plant woody shrubs e.g. pigeon peas that

provide both food and fuel


What do we call a ‚stove‘?

‚stove‘ = combination of

Heat-Generator +

Heat-Transfer- structure

Form of a ‚stove‘ depending on

fuel and cultural factors e.g.

cooking task (type of meal), type

of cooking (one-handed or two-

armed-full-upper-body-motion

needed), pot-shape and size etc.


Mud stove With clay liner

Clay stove

Food warmer or fireless cooker

Rocket Stove

Benefits of energy saving technologies

Small twigs

can generate

enough heat

for cooking

Saving up to

80% firewood

Sheltered fire,

less heat exposure

Smoke

reduction

Fast cooking,

less time


improved heat-transfer:

more cooking from heat

improved combustion:

burn the smoke and get

more heat from fuel


Rocket stove principle

A range of cookstoves to suit different needs and means

1 USD 8 USD 15 USD 20 USD 30 USD

50 USD 80 USD 50-100 USD 200 USD 300 USD


Institutional Rocket stoves

with Rocket stove with open fire


School feeding programme Mary‘s Meals Blantyre


How to get stoves out there: Implementation approaches

Rural Low- income Households Urban Low- income Households

portable

clay stove

Social marketing by

implementing partners

i.e. for ‘food&fuel’

fixed mud-stove

Difficult to find

suitable

strategy

portable HH Rocket stove

Local product too

expensive, imports

competitive Christa Roth: Stoves 101 - An introduction to biomass cookstoves on 28.1.2012 ETHOS Kirkland

Implementation approaches

Smallholder contract farmers Staff in company housing

Portable

clay stove

Social marketing

by contractor to

encourage

fuel-saving

Fixed (insulated)

‘Changu’ stove

Promotion by Agro-

industry, refinancing

through produce e.g.

Tea, Tobacco, Sugar

Fixed (solid)

‘Esperanza’ stove

Corporate Social Responsibility:

company builds stoves

in staff houses as

CSR activities


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New focus on emissions: WHO waking up to the fact that every year over 1.5 Mio people, mainly women and children, die from diseases attributed to or aggravated by exposure to smoke. ‚Smoke‘ claims more victims than breast cancer or malaria!

Global Alliance for Clean Cookstoves by the UN Foundation tries to address the problem by promotion of ‚clean‘ cookstoves, that reduce emissions by 90% and save 50% of the fuel compared to an open fire. Their ambitious aim is to disseminate 100 Mio clean cookstoves by 2020.


When do we get smoke?

Mainly from solid biomass fuels: Emissions= CO2, H2O, but also CO and PM

Wood => ‚smoke‘ (perceivable)

charcoal => CO (not perceivable)


Smoke = incomplete combustion

even ‚improved stoves‘

can smoke!

Factors:

fuelwood (too big, too wet,..)

Air (not enough, too cold,...)

Temperature (too cold...)

User / human factor

...so do we have solutions for

‚clean‘ stoves?


Biomass gasification: Gas-generation controllably

separated in space and time from gas-combustion

Raw

Bio-

mass

Heat

Water

vapour

Heat

Dry

Bio-

mass

Bio-

Char Ash

O2 from air

Char

gasifi-

cation

Pyrolysis

Carboni-

sation

dry-

ing

Combustion controlled Gas-Air-Mix

Solid

state

fuel

Gaseous

state

fuel

Emis-

sions

necessary inputs

for transformation

sufficient O2

Smoke

‚Wood‘-gas

time

Gas-generation

CO2 Water

vapour

Legend: solid Transformation Input Gas Output Design: Christa Roth

space

Gasifier - the new concept

Seperate control of

Generation and

combustion of gas from biomass

with very simple

means.

Air-controlled instead

of fuel-controlled

Gasifier: Batch-feeding of fuel, heat controlled by air regulation

conventional fires: constant feeding of fuel, unregulated air-supply


Gasifiers - an option for a quantum leap towards emission reduction

conven-tional

wood stoves

Gasifier

PM

discussed benchmarks 1500 mg

20 g

CO


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Gasifier for cooking depending on cooking task at hand

application lower than < 75 cm

Flame on top (no gas-conduct)

remember:

stove=

combination of Heat-Generator +

Heat-Transfer- structure


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Advantages of gasifiers compared to...

... conventional wood-fire: complete combustion (clean burning, less smoke, more useful thermal energy)

flexible use of a multitude of small-size renewable residues (e.g. rice

husks, nutshells, saw-dust etc.), no timber-based stick-wood or charcoal

... Biogas: Creation of gas from dry biomass with very simple inexpensive technology

directly in the burner unit (portable, no piping or special burner-head needed)

performance similar to biogas or LPG (but independent from water or digester)

... Solar cookers: cooking energy available on demand (independent from clear weather or

daylight hours )

... fossil Gas and Electricity: generate their own gas independent from imports or national providers

fuel can be collected or purchased at little cost and at own convenience


GIZ-HERA Manual Micro-gasification:

cooking on gas from biomass 1) ‘Wood-gas’ from biomass and its

application for cooking

2) Technologies and applications of micro-gasification to cookstoves

3) Feedstocks and fuels for micro-gasification

http://www.gtz.de/de/dokumente/giz2011-en-micro-gasification.pdf


http://www.gtz.de/de/dokumente/giz2011-en-micro-gasification.pdf

More information on Energypedia and the GIZ-HERA cooking energy compendium


Chapter from GIZ-HERA cooking energy compendium on


Cooking is central! FUEL

efficient

use of

firewood

smoke

reduction

kitchen

manage-

ment

firewood

manage-

ment

wood fuel

substitutes

HEALTH prevention

mitigation

heat

retainer

(hay box) FOREST

forest

manage-

ment

efficient

techno-

logies

FOOD

food

diver-

sification

nutrition

food

prepa-

ration

food

preser-

vation

food

& fuel

crops

cooking process


Thank you,

Please feel free to ask MANY questions


An Introduction to Improved Biomass Cookstoves

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